Definition

Childhood disintegrative disorder (CDD) or Heller's syndrome is a pervasive developmental disorder (PDD). PDDs are a spectrum of behavioural problems associated with autism and autism-like syndromes and may also be referred to as autistic spectrum disorders (ASD).

Pathogenesis

Childhood disintegrative disorder (CDD) differs from classical autism in that it occurs in children who have had previously normal development who then appear to regress.^[1] Some consider the condition to be a childhood dementia, suggesting that brain deposition of amyloid is the cause of the condition, although no clear-cut pathophysiology is proven.^[2]

Epidemiology

This is extremely rare with an incidence of 2 per 100,000 children.^[3]

• Prevalence of pervasive developmental disorder (PDD) is approximately 30 per 10,000 children and only 1 child out of 175 children with PDD has childhood disintegrative disorder (CDD).
• This makes it sixty times less frequent than autism.^[4]

Presentation

Symptoms

Affected children show clinically significant losses of earlier acquired skills in at least two of the following:

• Language, social skills or adaptive behaviour
• Bowel or bladder control
• Play
• Motor skills

The child presents after at least two years of apparently normal development. This occurs usually between the ages of 3 to 4 years, but generally before the age of 10 years.

• The onset may be abrupt or gradual.
• Usually parents and professionals have noticed no previous abnormalities in terms of language and non-verbal communication, social relationships, play, adaptive behaviour or emotional development.
• A typical presentation would be a child able to communicate in two- or three-word phrases, losing this ability. They would then stop talking altogether or retain only fragments of their former speech.
• There may be social and emotional problems, such as a child previously happy to be cuddled becoming averse to physical contact.

The patient shows similar social and communication deficits as those associated with autism. However, it is clearly distinguishable from autism on the basis of the normal antecedent developmental history.

• Children with childhood disintegrative disorder (CDD) are more likely than autistic children to show fearfulness and early stereotypical behaviours.^[5]
• Epilepsy occurs much more frequently in children with CDD compared with autism.^[6]
• The degree of intellectual impairment in children with CDD appears to be more 'even' than when compared with autism, although the overall degree of impairment and outcome appears to be similar in both groups.

Signs

• There are no specific confirmatory signs and physical abnormalities are not usually found, although there may be minor abnormalities such as microcephaly or motor incoordination.
• Careful CNS examination including fundoscopy is important to detect other possible causes of the symptoms.

Differential diagnosis

Any of the other pervasive developmental disorders (PDDs), childhood schizophrenia, or causes of mental retardation:

• Mercury poisoning
• Lead poisoning
• Aminoacidurias
• Hypothyroidism
• Brain tumour
• Organophosphate exposure
• Atypical seizure disorder
• Rett's syndrome
• HIV infection
• Other rare metabolic/neurodegenerative conditions

Investigations

Tests to exclude reversible underlying causes of the condition:

• FBC
• U&E/glucose
• LFT
• TFT
• Heavy metal levels
• HIV testing
• Urine screening for aminoaciduria

These are normally carried out during initial assessment in secondary care. EEG, MRI or CT scan are likely to be used to ensure an alternative diagnosis has not been missed.

Management

General measures

Therapy is given, as with autism, tailored to the child's disabilities, needs and educational objectives.

Pharmacological

• Risperidone may be effective in improving behavioural symptoms in pervasive developmental disorder (PDD),^[3] but there is little evidence of specific efficacy in childhood disintegrative disorder (CDD), due to its rarity.^[7]
• There is a significant risk of neuroleptic malignant syndrome with the use of neuroleptic medication.^[8]
• Other antipsychotics, stimulants and selective serotonin reuptake inhibitors (SSRIs) may be used in expert hands to help in the control of problematic behaviour.
• Epilepsy may require antiepileptic medication.

Prognosis

• Loss of skills often reaches a plateau and then there may be some limited improvement.
• In other cases there is progressive loss of skills.
• Those with moderate-to-severe mental retardation or with an inability to communicate tend to do worse than those left with a higher IQ and some verbal communication.^[8]
• The disorder is lifelong with long-term impairment of behavioural and cognitive functioning.
• Risk of seizures increases throughout childhood, peaking at adolescence and seizure threshold may be lowered by SSRIs and neuroleptics.

Historical note

In 1908 a Viennese remedial teacher, Theodor Heller, described six children who had insidiously developed a severe mental regression between the 3rd and 4th years of life after previously normal development. He called it dementia infantilis.